1. Field of the Invention
The present invention relates to LED lighting technology and more particularly, to a LED lighting device, which comprises a LED light housing consisting of a hollow outer shell, a reflector cup and a lens, and a LED light-emitting module having light-emitting diodes and a control circuit carried on a circuit board thereof, wherein the light-emitting diodes and a driver IC of the control circuit are arranged on a front side of the circuit board and a capacitor of the control circuit is arranged on an opposing back side of the circuit board, and thus, the surface area of the circuit board for circuit layout and the related circuit layout insulation distance are maximized.
2. Description of the Related Art
Lamps play a very important role in our daily life, and can provide bright illumination and clear visibility, allowing night activities to be carried out smoothly. In addition to indoor lighting, lamps can also be used for outdoor lighting, vehicle lighting as well as advertising lighting. However, conventional lamp bulb ort lamp tube type lighting devices have the drawbacks of quick light attenuation, high power consumption, large amount of waste heat and short lifespan. In order to reduce power consumption, power-saving lamp tubes are created. Further, in response to the demands of energy saving and carbon reduction and for the advantages of good photoelectric conversion efficiency, low power consumption, dimmable property, small size, quick response and long lifespan, light-emitting diodes (LEDs) are used for lighting to substitute for conventional incandescent and fluorescent lamp bulbs and tubes.
Further, fluorescent lamps are most popularly used for indoor lighting. Further, downlights are widely used in shops and department stores and installed in the ceilings or light steel frames in showcases or counters, enabling the emitted light to be focused on specific locations or commodities to attract people's eyes. However, conventional downlights have high brightness and can produce a high temperature during operation, causing thermal damage to commodities, counters, surrounding upholsteries. Further, the lifespan of fluorescent lamps will be relatively reduced when working in a high temperature environment for a long time.
In order to solve the aforesaid various lighting problems, many lighting device manufacturers use light-emitting diodes in their lighting devices to substitute for conventional fluorescent lamp bulbs or tubes, and provide lighting devices with different heat dissipation designs for quick dissipation of waste heat during operation of the light-emitting diodes. FIGS. 7 and 8 illustrate a LED lighting device according to the prior art. As illustrated the LED lighting device comprises a LED light housing A, a LED light-emitting module B and an electrical module C. The LED light housing A comprises an outer shell A1, which comprises an accommodation chamber A10, a flat mounting surface A11 disposed in a top side inside the accommodation chamber A10 and an annular heat dissipation space A12 extending around the annular heat dissipation space A12, a mounting through hole A13 cut through the center of the flat mounting surface A11 and the top wall of the outer shell A1, a light transmissive bottom cover A2 covering the bottom side of the accommodation chamber A10 of the outer shell A1, and a top cover A3 capped on the top side of the outer shell A1. The electrical module C comprises a main control circuit board C1 mounted on the top side of the outer shell A1 and covered by the top cover A3, and a power cord C11 extended from the main control circuit board C1 to the outside of the top cover A3 for connection to an external power source. The LED light-emitting module B comprises a LED circuit board B1 mounted on the flat mounting surface A11 inside the accommodation chamber A10 of the outer shell A1, an array of light-emitting diodes B2 arranged on the circuit board B1, and a power cord B11 extended from the LED circuit board B1 and inserted through the mounting through hole A13 of the outer shell A1 and then electrically coupled to the main control circuit board C1. When the light-emitting diodes B2 are electrically conducted to emit light through the light transmissive bottom cover A2 for illumination, generated waste heat is gathered in the annular heat dissipation space A12 around the flat mounting surface A11 and then transferred through the peripheral wall of the outer shell A1 to the outside open air for quick dissipation.
Further, US Environmental Protection Agency updated ENERGY STAR Lamps Specification Version 2.0 to pursue higher efficacy levels and a broader scope of the specification in terms of the types of lamps. This ENERGY STAR Lamps Specification Version 2.0 is more critical on the operation of integrated LED light source, the efficiency of no-load mode, the condition of flashing in dimming, driver on board (DOB) under SMT architecture, the use of electrolytic capacitor (E-CAP) to solve the problem of flashing and to match with TRIAC in dimming. However, because the circuit board B1 of the LED light-emitting module B of the aforesaid prior art LED lighting device is fixedly fastened to the flat mounting surface A11 of the outer shell A1 with screws, the circuit board B1 needs to provide multiple mounting through holes for the mounting of the screws. Making these mounting through holes on the circuit board B1 relatively reduces the available surface area of the circuit board B1 for circuit layout and the related circuit layout insulation distance, limiting the flexibility of the use of the overall space. Further, the power driver of the main control circuit board C1 converts AC to DC for driving the light-emitting diodes B2. The use of this design of power drive greatly increases the cost of the electrical module C. Further, the operation of the power driver of the main control circuit board C1 to step down the voltage of the inputted AC power causes a certain amount of power conversion loss. Improvements in this regard are desired.